This invention relates to athletic shoes and more particularly, has for its purpose the provision of such athletic shoes which avoid any overpronation of the foot during running, are comfortable to mear and have good durability.
The human anatomy is such that when a person runs, at each step the rear portion of the heel of the foot makes initial contact with the ground, followed by the heel proper, the outside edge of the foot adjacent to the arch, the ball of the little toe and the ball of the big toe in that order, and finally the big, second, third, fourth and little toe effect the toe-off motion. This motion of the foot is accompanied by a shift of the person's body weight thereon. It has been known that the foot excessively rolls inward, that is to say, overpronates depending upon the cushioning of a midsole of a shoe in the course of the initially contacting motion of the heel to the subsequent contacting motion of the foot. Such overpronation causes, trouble with the knee joint.
Japanese Patent Public Disclosure 58-49101 discloses an athletic shoe sole adapted to preclude overpronation wherein a midsole has hard cylindrical stabilizers embedded in the inside portion of the heel. The hard cylindrical stabilizers reduce shock absorption in the heel inside portion of the midsole to result in uncomfortable shoes. A combination of good cushioning of the middle and hardness of the stabilizers also results in damage to the midsole at the interfaces therebetween the reduce the durability of the shoes.